A simulation method for describing the diffusion processes of adsorbed atoms on a covalently bound surface was presented. The method took advantage of the benefits of the Monte Carlo technique for extending the time-scale in simulations, and it was independent of the lattice type of the surface. It was particularly useful in the study of the diffusion processes on a surface with structural and/or chemical inhomogeneity. As a simple illustration of the method, it was used to study hydrogen diffusion on a relaxed regular diamond {111} surface and an irregular diamond {111}-like surface. Four and five local minima for adsorption of a hydrogen atom were found on the regular diamond {111} surface and the irregular surface, respectively. The activation energies, the vibrational frequencies and the total escape rates of the hydrogen atom at each minimum were determined. The mean square displacement and diffusion constant of the hydrogen atom on the surfaces were also calculated. The results indicated that the Monte Carlo method was effective in investigating the diffusion processes of atoms on an arbitrary surface.

Monte Carlo Method for Simulations of Adsorbed Atom Diffusion on a Surface. Y.H.Liu, E.Neyts, A.Bogaerts: Diamond and Related Materials, 2006, 15[10], 1629-35